Texas Instruments' Half Duplex system looks very similar to the Full Duplex system. However, there is an additional charge capacitor in the transponder. When instructed, the reader activates its transmitter for 50 ms, which is long enough to charge the capacitor. The transmitter is then turned off and the transponder responds using the energy stored in the capacitor. Half Duplex means that signals are only traveling in one direction at a time. More importantly, the tag does not have to compete with any noise associated with the powerful carrier signal. The response signal is frequency modulated which allows superior performance in noisy conditions and a better ability to discriminate between closely spaced tags.